:root{
    --ink:#122436; --ink-soft:#3c5163;
    --paper:#eef2f2; --paper-card:#ffffff; --line:#c9d3d2;
    --delft:#1e3a5f; --delft-deep:#0f2340;
    --gold:#c98a1f; --wine:#8c2a3a; --teal:#1f6f78;
    --radius:3px;
  }
  *{box-sizing:border-box;}
  body{margin:0;background:var(--paper);color:var(--ink);font-family:system-ui,"Microsoft YaHei",sans-serif;line-height:1.55;}
  h1,h2,.serif{font-family:Georgia,"Microsoft YaHei",serif;}
  .wrap{max-width:820px;margin:0 auto;padding:40px 24px 80px;}
  header.page-head{border-bottom:1px solid var(--line);padding-bottom:28px;margin-bottom:28px;}
  header.page-head h1{font-size:clamp(26px,4vw,34px);font-weight:700;margin:0 0 10px;color:var(--delft-deep);letter-spacing:-0.01em;}
  header.page-head p{max-width:600px;color:var(--ink-soft);font-size:15px;margin:0;}

  .site-nav{background:var(--delft-deep);border-bottom:1px solid #0a1c30;}
  .site-nav-inner{max-width:1080px;margin:0 auto;padding:14px 24px;display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:10px;}
  .site-nav .brand{font-family:Georgia,"Microsoft YaHei",serif;font-size:17px;font-weight:700;color:#fff;text-decoration:none;letter-spacing:-0.01em;}
  .site-nav nav{display:flex;gap:4px;flex-wrap:wrap;}
  .site-nav nav a{color:#cdd9e3;text-decoration:none;font-size:13.5px;padding:7px 12px;border-radius:var(--radius);}
  .site-nav nav a:hover{background:rgba(255,255,255,0.08);color:#fff;}
  .site-nav nav a.current{background:rgba(255,255,255,0.14);color:#fff;font-weight:600;}

  .card{background:var(--paper-card);border:1px solid var(--line);border-radius:var(--radius);padding:24px 26px;margin-bottom:22px;}
  .card h2{font-size:16px;margin:0 0 14px;color:var(--delft-deep);}

  .q-block{margin-bottom:18px;}
  .q-block .qtext{font-size:14px;font-weight:600;margin-bottom:10px;}
  .opt-row{display:flex;gap:10px;flex-wrap:wrap;}
  .opt-row button{
    font-family:inherit;font-size:13.5px;padding:9px 16px;
    border:1px solid var(--line);border-radius:var(--radius);background:#fff;color:var(--ink);cursor:pointer;
  }
  .opt-row button.selected{border-color:var(--delft);background:#eaf0f6;color:var(--delft-deep);font-weight:600;}

  .verdict{border-radius:var(--radius);padding:18px 20px;margin-bottom:20px;display:none;}
  .verdict.show{display:block;}
  .verdict.possible{background:#e5f2ee;border:1px solid #c3ddd2;color:#1f6f4a;}
  .verdict.impossible{background:#f7ecec;border:1px solid #e6c9c9;color:var(--wine);}
  .verdict h3{margin:0 0 6px;font-size:16px;}
  .verdict p{margin:0;font-size:13.5px;}

  ul.checklist{margin:0;padding-left:20px;}
  ul.checklist li{margin-bottom:10px;font-size:14px;}

  .note{margin-top:20px;font-size:12.5px;color:var(--ink-soft);border-top:1px solid var(--line);padding-top:16px;}